Cell bounding box drawing between widgetsets

[Jonny]

I am trying to make my application look the same (or similar enough!) on GTK2, QT5, QT6 and Windows widgetsets (hopefully one day macOS - if I ever gain access to one).

There is a slight visual "glitch" with stringgrid cells:

- qt5 - the left side edge of text starts before the bounding area
- qt6 - the right side of the bounding box extends to the adjacent cell

I know that these are very minor, but can someone tell me what to edit to fix these, please?

Screenshot attached comparing gtk2, qt5, qt6, windows - and a sample project.